Hydraulic lift



Jan. 11, 1966 A. s. LONDON 3,228,658

HYDRAULIC LIFT Filed Dec. 11, 1963 FIGZI IN VENTOR 52 ALVA/V 6. LONDONUnited Sates Patent 3,225,658 HYDRAULIC LEFT Alvan G. London, Wanwatosa,Wis, assignor to Applied Power industries inc, Miiwaukee, Wis, acorporation of Wisconsin Filed Dec. 11, 1963, Ser. No. 329,629 7 Claims.(Cl. 254-915) This invention relates to an improved hydraulic lift andrelates more particularly to an improvement in hydraulic jackconstructions wherein the safety mechanism for the system is formed as apart of the base of the cylinder.

A principal objective of this invention is to reduce the chance ofaccidents caused by conduit ruptures and other losses of system pressurewhen a load is in an elevated or otherwise supported position.

A further objective of the invention is to provide a system wherein asingle manually operated release valve at the fluid source acts as alocking valve as well as a release control valve for draining fluid tothe reservoir during a load lowering operation.

A still further objective of the invention is to provide a hydraulicjack assembly wherein the load can be locked into position at any pumpstroke position of the power source.

Another objective of this invention is to provide a fluid locking meanswithin a jack assembly wherein the safety locking mechanism of theassembly is constructed in the cylinder base.

A still further objective of the invention is to provide a positiveoperating, inexpensive, rugged and uncomplex breaking fuse for use withhydraulic lifting assembles.

Another important objective of the invention is to provide a combinedsystem wherein the locking arrangement is opened by merely actuating thepump to increase pressure in an expansion cylinder.

These and other important objectives and advantages of the inventionwill hereinafter become more fully apparent from the followingdescription of the drawings, illustrating a presently preferredembodiment thereof, and wherein:

FIGURE 1 is a partially diagramamtic-schematic crosssectional view ofthe principal elements of the invention; and

FIGURE 2 is an enlarged portion of FIGURE 1.

Referring now to the drawings wherein like elements indicate like parts,the numeral 10 indicates the jacking assembly of this invention. Theassembly is comprised generally of a pump 12, a fluid reservoir 14, ahydraulic jack 16, and a manual-type adjustable opening valve 18. Valve18 may be of the needle stem variety. A conduit 20 leads from thehydraulic jack 16 to pump 12, and a second conduit 22 from the hydraulicjack to reservoir 14. The valve 18 is across conduit 22. In commonpractice, the pump and fluid reservoir are in a common housing andconduit 22 is oftentimes no more than a short passageway interrupted bya valve. The reservoir pressure is normally atmospheric.

Slidably received within the cylinder 23 of jack 16 is the piston rod 26having an outer end 32 extending through the upper end 28 of thecylinder. This upper or load end 28 of cylinder 23 defines an openingvia a suitable bearing seal 30 through which the piston rod r 3,228,658Patented Jan. 11, .1966

26 is slidably received. The outer end 32 supports a load which is movedin concert with the piston rod. The other or lower end 34 of thecylinder is closed by way of a solid base member 36.

Formed in base 36 is a cross bore 38 having a central axis generallyperpendicular to the longitudinal axis of the cylinder. An opening 40generally parallel to the longitudinal axis of the cylinder communicatesthe bore 38 with an expansion chamber 42 formed between the piston rod26 and the base 36. Opening 40 is enlarged at 44 to receive a fluidstraining or filter screen 46.

At one end bore 38 is equipped with a conduit plug 50 which is adaptedto receive the conduit 20. The other end of the bore is closed by astandard sealing plug 52. Intermediate the plugs 50 and 52 the bore 38is formed with a reduced annular section 54 which acts on one sidethereof as a valve seat 57 for a valve ball 56. The other side ofsection 54 provides a ledge 58 to which a first end of the cylindricalscrew plug 60 abuts. The plug 60 is interiorly threaded at 62 to receivethe exteriorly threaded spring adjustment screw 66. A spring 68 extendsthrough the valve seat and engages the ball 56 at one end and the ring66 at the other. The spring is of sufiicient length and strength tomaintain the ball in spaced relationship with its valve seat undernormal conditions of fluid flow. The fluid velocity necessary to seatball 56 against the bias of spring 68 is adjustable by the longitudinalposition of screw 66 along plug 60.

A second spring 70 serves to maintain a second fluid screening member 72over opening 62.

In operation fluid is pressurized in pump 12 and is delivered to theexpansion chamber 42 via conduit 20, cross-bore 38 and opening 40. Byfollowing this path, the fluid passes through the two straining members46 and 72, through the valve seat 57, around the ball 56 and throughopening 40. During the pumping operation, ball 56 will not tend to.closethe fluid path since fluid flow is from conduit 20 to the expansionchamber 42. Pumping is continued until the piston rod 26 raises the loadto the desired level.

To lock the load at this desired level, the fluid in chamber 42 must betrapped. This can be accomplished by causing a full opening of valve 18such that a reverse flow of high velocity toward the reservoir iscommenced. This velocity is sufficient to overcome the bias of spring 68and consequently ball 56 will engage with seat 54. The pressure causedby the raised load will safely position the ball against the seat aslong as pressure in chamber 42 exceeds the pressure in line 20.

In order to unseat the ball 56, valve 18 is closed and pump 12 is givenseveral additional strokes suflicient to exceed the pressure in chamber42. The ball 56 is, therefore, unseated so that normal drainingoperations can occur through the base 36. Valve 18 is then partiallyopened to act as a metering device for lowering the load.

It will be understood that a loss of pressure in pump 12 or a rupture inany of the conduit systems will cause a reaction exactly the same as afull opening of valve 18. Indicia such as lock, lower and raise canconveniently be applied to respectively designate the open, metering andclosed positions of the valve.

In a general manner, while there has been disclosed in the abovedescription what is deemed to be the most practical and efficientembodiment of the invention, it should be well understood that theinvention is not limited to such an embodiment as there might be changesmade in the arrangement, disposition, and form of the parts withoutdeparting from the principle of the present invention as comprehendedwithin the scope of the accompanying claims.

I claim:

1. A hydraulic device for loading and unloading a pressure chambercomprising a base closing one end of said chamber, said base having abore formed therein, a fluid power source, a first fluid conduit meanscommunicating said power source to said bore, a second conduit meanscommunicating said first conduit means to a fluid reservoir having areservoir pressure, an adjustable valve along said second conduit means,said base having a passageway communicating said bore with said chamber,a reduced portion along said passageway defining a valve seat, a bearingsurface between said reduced portion and said first conduit means, avalve member in said passageway for closing said valve seat, a springsupported on said surface and extending into said passageway inengagement with said member for normally biasing said member in spacedrelationship with said seat, said adjustable valve having a firstsetting wherein fluid in said chamber under pressure higher than saidreservoir pressure will return to said reservoir without overcoming thebias of said spring and a second setting pemitting fluid flow ofsufficient velocity to overcome the bias of said spring and cause thepressure in said chamber to force said member against said valve seatand thereby close said passageway.

2. An improved hydraulic jack comprising in combination, a cylinderhaving a load end and a base end, a piston rod slidably received in saidcylinder and extending through said load end, a base closing said baseend of said cylinder and defining an expansion chamber with said piston,said base having a bore formed therein, a fluid power source, a firstfluid conduit means communicating said power source to said bore, asecond conduit means communicating said first conduit means to a fluidreservoir having a reservoir pressure, an adjustable valve along saidsecond conduit means, said base having a passageway communicating saidbore with said expansion chamber, a reduced portion along saidpassageway defining a valve seat, a bearing surface between said reducedportion and said first conduit means, a valve member in said passagewayfor closing said valve seat, a spring supported on said surface andextending into said passageway in engagement with said member fornormally biasing said member in spaced relationship with said seat, saidadjustable valve having a first setting wherein fluid under .a pressurehigher than said reservoir pressure in said chamber will return to saidreservoir without overcoming the bias of said sping and a second settingpermitting fluid flow of suflicient velocity to overcome the bias ofsaid spring and cause the pressure in said chamber to force said memberagainst said valve seat and thereby close said passageway.

3. The device described in claim 1 wherein said hearing surface ismovable toward and away from said reduced portion.

4. An improved hydraulic jack comprising in combination, a cylinderhaving a load end and a base end, a piston slidably received in saidcylinder, a load supporting piston rod attached to said piston andextending through said load end, a base closing said base end of saidcylinder and defining an expansion chamber with said piston, said basehaving a bore formed therein, a fluid power source, a first fluidconduit means communicating said power source to said bore, a secondconduit means communicating said first conduit means to a fluidreservoir, an adjustable valve along said second conduit means, saidbase having a passageway communicating said bore withsaid expansionchamber, a reduced portion along said passageway defining a valve seat,a bearing ledge in said passageway between said reduced portion and saidpower source, a valve ball in said passageway for closing said valveseat,

a spring supported on said ledge and extending into said passageway inengagement with said ball for normally biasing said ball in spacedrelationship with said seat, said spring having a strength which isovercome by a predetermined fluid flow velocity from said expansionchamber to said bore whereby a loss of pressure between said bore andsaid pump or reservoir suflicient to cause said fluid flow velocity willcause said ball to engage said seat when said expansion chamber ispressurized.

5. An improved hydraulic jack comprising in combination, a cylinderhaving a load end and a base end, a piston slidably received in saidcylinder, a load supporting piston rod attached to said piston andextending through said load end, a base closing said base end of saidcylinder and defining an expansion chamber with said piston, said basehaving a bore formed therein, a fluid power source, a first fluidconduit in communication with said power source, a second conduit incommunication with a fluid reservoir means communicating said first andsecond conduits to said bore, an adjustable valve along said secondconduit, said base having a passageway communicating said bore with saidexpansion chamber, a first fluid filter in said bore and a second fluidfilter in said passageway, a reduced portion along said passagewaydefining a valve seat on one side thereof and an abutment on the otherside thereof, a cylindrical plug having one end against said abutment,an inwardly directed annular flange about the other end of said plugdefining a pass-through aperture, a valve ball in said passageway forclosing said valve seat, a spring supported by said flange and extendinginto said passageway in engagement with said ball for normally biasingsaid ball in spaced relationship with said seat, said adjustable valvehaving a first setting wherein fluid in said chamber under pressurehigher than said reservoir pressure will return to said reservoirwithout overcoming the bias of said spring and a second settingpermitting fluid flow of suflicient velocity to overcome the bias ofsaid spring and cause the pressure in said chamber to force said ballagainst said valve seat and thereby close said passageway.

6. A hydraulic device for loading and unloading a pressure chambercomprising a base closing one end of said chamber, said base having abore formed therein, a fluid hand pump, a first fluid conduitcommunicating said hand pump to said bore, a second conduitcommunicating said bore through a portion of said first conduit to afluid reservoir having a reservoir pressure, an adjustable valve alongsaid second conduit, said base having a passageway communicating saidbore with said chamber, a reduced portion along said passageway defininga valve seat, a bearing surface between said reduced portion and saidfirst conduit, a ball in said passageway for closing said first conduit,a ball in said passageway for closing said valve seat, a springsupported on said surface and extending into said passageway inengagement with said ball for normally biasing said member in spacedrelationship with said seat, said adjustable valve having a lowersetting wherein fluid in said chamber under pressure exceeding saidreservoir pressure will return to said reservoir without overcoming thebias of said spring and a lock setting permitting fluid flow ofsuflicient velocity to overcome the bias of said spring and cause thepressure in said chamber to force said member against said valve seatand thereby close said passageway, and a third raise setting in whichthe path to said reservoir is completely closed and the path betweensaid hand pump and chamber is open.

7. A hydraulic system for loading and unloading a pressure chambercomprising a base enclosing one end of said chamber, said base having abore formed therein, a fluid power source, a first fluid conduitcommunicating said power source to said bore, a second conduitcommunicating said first conduit to a fluid reservoir, having areservoir pressure, an adjustable valve along said sec- 0nd conduit,said base including a passageway communicating said bore with saidchamber, a valve seat between said passageway and said bore, a bearingsurface between said valve seat and said first conduit, a valve memberin said passageway for closing said valve seat, a spring supported onsaid surface and extending into said passageway to engagement with saidmember for normally biasing said member in spaced relationship with saidseat, said adjustable valve having a first setting wherein fluid underpressure in said chamber at a pressure higher than said reservoirpressure will return to said reservoir without overcoming the bias ofsaid spring, a second setting permitting fluid flow to said reservoir ofsufiicient velocity to overcome the bias of said spring and cause thepressure in said chamber to force said member References Cited by theExaminer UNITED STATES PATENTS 2,136,898 11/1938 Thomas 137-5172,424,741 7/ 1947 Chambers. 2,541,282 2/1951 Powers l375l7 X WILLIAMFELDMAN, Primary Examiner.

MILTON S. MEHR, Examiner.

1. A HYDRAULIC DEVICE FOR LOADING AND UNLOADING A PRESSURE CHAMBERCOMPRISING A BASE CLOSING ONE END OF SAID CHAMBER, SAID BASE HAVING ABORE FORMED THEREIN, A FLUID POWER SOURCE, A FIRST FLUID CONDUIT MEANSCOMMUNICATING SAID POWER SOURCE TO SAID BORE, A SECOND CONDUIT MEANSCOMMUNICATING SAID FIRST CONDUIT MEANS TO A FLUID RESERVOIR HAVING ARESERVOIR PRESSURE, AN ADJUSTABLE VALVE ALONG SAID SECOND CONDUIT MEANS,SAID BASE HAVING A PASSAGEWAY COMMUNICATING SAID BORE WITH SAID CHAMBER,A REDUCED PORTION ALONG SAID PASSAGEWAY DEFINING A VALVE SEAT, A BEARINGSURFACE BETWEEN SAID REDUCED PORTION AND SAID FIRST CONDUIT MEANS, AVALVE MEMBER IN SAID PASSAGEWAY FOR CLOSING SAID VALVE SEAT, A SPRINGSUPPORTED ON SAID SURFACE AND EXTENDING INTO SAID PASSAGEWAY INENGAGEMENT WITH SAID MEMBER FOR NORMALLY BIASING SAID MEMBER IN SPACEDRELATIONSHIP WITH SAID SEAT, SAID ADJUSTABLE VALVE HAVING A FIRSTSETTING WHEREIN FLUID IN SAID CHAMBER UNDER PRESSURE HIGHER THAN SAIDRESERVOIR PRESSURE WILL RETURN TO SAID RESERVOIR WITHOUT OVERCOMING THEBIAS OF SAID SPRING AND A SECOND SETTING PERMITTING FLUID FLOW OFSUFFICIENT VELOCITY TO OVERCOME THE BIAS OF SAID SPRING AND CAUSE THEPRESSURE IN SAID CHAMBER TO FORCE SAID MEMBER AGAINST SAID VALVE SEATAND THEREBY CLOSE SAID PASSAGEWAY.